The boy had been in critical condition following an alleged beating by the boyfriend of his mother, police said.

The man accused in the case, Joseph Patterson, 27, was initially charged in Lincoln County with aggravated assault and aggravated battery on an infant, but those charges could be reviewed in light of the boy’s death, NFL.com reported. Patterson had a court appearance Friday and was ordered held on $750,000 cash bond.

Peterson, who missed practice Thursday to attend to what was termed as a “serious personal matter,” had said earlier Friday upon his return that he was certain he would play Sunday when the Vikings host the Carolina Panthers. However, that was before his son passed away.

Peterson declined to speak Friday specifically about the situation, asking reporters to respect his and his family’s privacy. His father, Nelson Peterson, told the St. Paul Pioneer Press that one of Peterson’s sons was in critical condition at a hospital in Sioux Falls.

Police described the child’s condition at the time as consistent with abuse.

Jane Bammert, owner of the Little Coalinga Bar, told The Associated Press that Peterson stopped by the Sioux Falls restaurant on Thursday for a turkey sandwich.

Peterson smiled politely while he took questions after practice Friday, but he spoke softly with a somber expression with dozens of cameras, recorders and media members surrounding him in the locker room.

“I’ll be ready to roll, focused,” Peterson said, looking ahead to the game Sunday against Carolina at 1 p.m.

Peterson is second in the NFL with 421 yards rushing and first in the league with five touchdowns.

“Football is something I will always fall back on,” Peterson said. “It gets me through tough times. Just being around the guys in here, that’s what I need.”

Later Friday, after news of the boy’s death spread, Peterson thanked his family, fans and even fans of other NFL teams for their support.

He tweeted: “The NFL is a fraternity of brothers and I am thankful for the tweets, phone calls and text messages from my fellow players.”

Dozens of current and former professional athletes wished Peterson well on Twitter, expressing support, offering prayers and voicing disgust about the alleged abuse.

“Sick for my friend. Strong guy but this one will bring the strongest down,” tweeted NBA star LeBron James.

The Panthers, this week’s opponent, were sympathetic.

“It’s absolutely terrible. Our thoughts and prayers go out to him and his family, and hopefully things work out,” coach Ron Rivera said.

Vikings coach Leslie Frazier said he thought Peterson practiced as well as he could Friday considering the circumstance.

“He seems like he was into it, engaged in what he had to get done,” Frazier said. “Obviously, tough. He’s human. But he was into it mentally, best as he could be.”

Fellow running back Toby Gerhart said: “It’s hard for any man to admit that he’s hurting or he needs help or anything like that. For us to be around him and tell him we’ve got his back, if there’s anything he needs that we’re there for him, I think that goes a long way.”